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What type of structures can subterranean organs be derived from?
Which of the following is NOT a type of subterranean stem?
What characteristic distinguishes subterranean stems from roots?
Which carbohydrate compound is commonly abundant in subterranean organs?
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Which of the following statements about underground organs is true?
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Which structure is classified as an underground root?
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What can be a distinguishing feature of commercial rhizomes compared to roots?
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What is one of the main differences in appearance between subterranean stems and roots?
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What is the primary function of the root in plants?
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Which component of the root is responsible for the growth of lateral branches?
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How does the primary root system differ between dicots and monocots?
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What is a characteristic feature of the piliferous layer of the young dicot root?
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What type of root system develops from the radicle in dicot plants?
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Which type of roots arise from the stem and are not derived from the primary root?
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Which of the following is NOT a function of roots?
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What is a defining histological feature of the cortex in young roots?
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What characteristic of the Spanish liquorice root contributes to its sweet taste?
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What happens to the roots and rhizomes of liquorice after they are harvested?
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Which part of the rhizome does NOT typically have a presence in its structure?
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What distinguishes the peeled liquorice from the unpeeled liquorice in terms of color?
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What type of xylem is present in the center of the liquorice root?
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Which of the following components is found in the phloem of the liquorice root?
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What structures are removed before the drying process of liquorice roots?
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What happens to the taste of unpeeled liquorice as it is tasted?
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What is the primary benefit of deglycyrrhizinated liquorice (DGL) in the treatment of ulcers?
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Which of the following conditions is glycyrrhetic acid commonly used to treat?
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What effect does excessive consumption of liquorice particularly cause?
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Which type of liquorice is effective as an expectorant?
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What is one of the major protective effects of liquorice on the liver?
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In which of the following situations would you NOT use deglycyrrhizinated liquorice?
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What form do the antimicrobial and antiviral activities of flavonoid components take?
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Which characteristic does glycyrrhizin mimic that allows it to be used in certain treatments?
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What characteristic feature is observed in the wood parenchyma of the liquorice?
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What is the primary function of triterpenoidal saponins found in liquorice?
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What type of starch granules are primarily found in liquorice?
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In the structure of the liquorice, where are the medullary rays found?
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What effect does hydrolysis of glycyrrhizin have on its properties?
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Which type of wood vessels are characterized in liquorice?
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What role does the cork serve in the liquorice plant anatomy?
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What is the primary characteristic of the powder derived from peeled liquorice?
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Study Notes
Subterranean Organs
- Subterranean organs are plant parts growing underground, either of root or stem origin
- Stem structures include corms, bulbs, stem tubers and rhizomes
- Root structures include true, adventitious roots, and root tubers
- They lack chlorophyll and are commonly used as storage organs in perennial plants
- They are rich in carbohydrates like starch, sugars and inulin
Differences between Subterranean Stems and Roots
- Stems have nodes and internodes while roots do not
- Stems have scale leaves and axillary buds, roots do not
- Stems have mainly transverse wrinkles, roots have mainly longitudinal wrinkles
- Stems contain wide pith in the center, roots have a solid mass of xylem vessels without pith
- Stems have pericycle, roots do not
The Root
- The root grows vertically downward into the soil, away from light
- It lacks nodes, internodes, leaves and buds
- It's growing point is covered by the root cap
- Root branching is described as endogenous, originating from the pericycle
- Dicot roots develop into a tap root system, while monocot roots develop into a fibrous root system
- The root is composed of four zones: the growing point, zone of elongation, zone of root hairs and zone of lateral branches
Root Functions
- Absorption of water, minerals and organic compounds from the soil
- Anchoring the plant in the ground
- Serving as a storage organ
- Propagation
Types of Roots
- Primary roots develop into tap roots (e.g., Senega, Belladonna)
- Secondary roots are lateral roots (e.g., Krameria)
- Adventitious roots originate from the stem (e.g., Ipecacuanha)
- Storage roots are swollen with reserve food materials
- Tuberous roots are very swollen, e.g., Jalap
Histology of the young root (primary root)
- Piliferous layer: single row of thin-walled cells lacking stomata, cuticle and intercellular spaces, with root hairs
- Cortex: wide and parenchymatous
Radix Glycyrrhizae (Liquorice)
- The dried peeled or unpeeled root and rhizome of Glycyrrhiza glabra variety typica (Spanish Liquorice)
- G. sources grow in Spain, France, England, Italy, Germany and USA
- Stolons are horizontal underground stems that produce new plants from their nodes
Spanish Liquorice
- Stolons with few pieces of roots, cylindrical shape, unbranched
- Unpeeled color: dark brown or reddish-brown; peeled color: yellow
- Fracture is fibrous, internally bright yellow
- Stolons bear small buds, scaly leaves, and scars of slender side roots
- Roots bear small rootlet scars
- Peeled liquorice has very sweet taste, unpeeled has a sweet taste followed by bitterness
Microscopical Characters
- Liquorice rhizomes and roots have typical structure except for the absence of pith and pericycle in the root
- The root has tetrarch primary xylem in the center
- The rhizome shows layers including cork, phelloderm, pericycle, phloem, cambium, secondary xylem, medullary rays and pith
- The peeled liquorice lacks cork, cortex and sometimes part of the phloem
Powder
- Light-yellow in peeled, brownish-yellow in unpeeled
- Faint characteristic odour and very sweetish taste
- Microscopical features include starch granules, prismatic crystals of calcium oxalate, cork cells, fibres, vessels, fibres of pericycle, phloem, xylem, wood parenchyma and medullary ray cells
Active Constituents
- Triterpenoidal saponins: glycyrrhizin (5–7%), a glycoside 50 times sweeter than sugar
- Glycyrrhein: very sweet taste, hydrolysis results in glycyrrhetic acid (loses sweet taste) and 2 molecules of glucuronic acid
Uses
- Expectorant: loosens and thins mucus
- Demulcent: relives internal membrane inflammation
- Antiulcerogenic activity: used in treatment of stomach and deudenal ulcers
- Glycyrrhetic acid has deoxycorticosterone effect: used in treatment of rheumatoid arthritis, inflammatory conditions and Addison's disease
- Flavonoid components: antimicrobial and antiviral activity (externally as a gel)
- Glycyrrhetic acid has hormonal activity: estrogenic action, used as a starting material for semi-synthesis of cortisone and sex hormones
- Prevent liver toxicity: through membrane stabilization, inhibiting viral C multiplication and inducing interferon production
Two Types of Liquorice
- "Standard" liquorice
- "De-glycyrrhizinated" liquorice (DGL): glycyrrhizin is removed
- Each type is suitable for different conditions
Uses
- Expectorant: effectively liquefies mucus
- Demulcent: relieves internal membrane inflammation
- Hyperacidity: removes irritating effects of acids
Antiulcerogenic activity
- Deglycyrrhizinated liquorice (DGL): useful for treating ulcers due to flavonoids that kill Helicobacter pylori
Deoxycorticosterone effect
- Glycyrrhizin's action is similar to adrenal cortex hormones, especially desoxycorticosterone, used to treat rheumatoid arthritis, inflammatory conditions and Addison's disease
Antimicrobial and antiviral activity
- Flavonoid components have antimicrobial and antiviral activity (externally as a gel)
Side Effects and Contraindications
- Excessive liquorice consumption can lead to "mineralocorticoid syndrome"
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Description
Explore the fascinating world of subterranean organs, including the differences between subterranean stems and roots. Understand how these structures function as storage organs for carbohydrates and learn about their unique characteristics. This quiz delves into essential plant biology concepts related to underground growth.
